		TAP - Universal Magtape Reader
		==============================

     TAP is a program to handle magtapes of unknown format, or magtape
     of  a  format  which  FLX  and PIP cannot handle. It provides the
     facility  both  for listing out information about a tape, and for
     transferring information from the tape to a file on disk. It also
     allows  for  conversion of specified fields (or the whole record)
     from  EBCDIC  to ASCII, the truncation of input records to remove
     trailing  blanks.  TAP  will  handle  either  file-structured  or
     non-file-structured tapes.


     The command line for TAP is one of the following  formats:-

          1.  TAP TP:/INPSW for getting information
     or
          2.  TAP filespec/OUTSW = TP:/INPSW for performing a transfer.

	For a list of valid switches type HELP TAP SWITCHES.
	For help on an individual switch type HELP TAP <switch>.
	For an explanation of the commandline type HELP TAP FORMAT.
2	FORMAT
     The command line for TAP is one of the following  formats:-

          1.  TAP TP:/INPSW for getting information
     or
          2.  TAP filespec/OUTSW = TP:/INPSW for performing a transfer.
     where:-

     TP:  is the magtape device name in the format:-

        MTn:  for TU10 or TE10
        MMn:  for TU16 or TE16
        where n is an (optional) single-digit unit number.

     Filespec is a standard RSX file specification

     /INPSW represents some combination of input switches.

     /OUTSW represents some combination of output switches.
2	SWITCHES
     Valid input switches are:

          /LI       List block sizes
          /FU       List blocks
          /BL:n:m   Only consider blocks n to m
          /FI:n     Only consider file n
          /FX:n:m   Read fixed-length records (n bytes long) from tape
                    and  create fixed length records (m bytes long) on
                    disk.
          /EB:n1:m1:n2:m2... Convert  specified  fields from EBCDIC to
                    ASCII
          /PE       Magtape is phase-encoded.

     Valid output switches are:

          /AP       Append to existing file.
          /CO       Create output file contiguous.
          /CR       Create  output  file  in  Carriage  Return format.
                    (default)
          /FX:n:m   As for input 
          /TR       Remove trailing blocks from output.

     Type HELP TAP <switch> for help on a particular switch.
2	/LI

     /LI       List  on  requesting terminal numbered tape blocks with
               their size in bytes.
2	/FU

     /FU       Same  as /LI but also lists out contents of each block,
               80 chars to a line.
2	/BL

     /BL:n:m   Specifies  that  only  tape  blocks  n  to  m are to be
               considered.  n  and  m  are  decimal  and  must both be
               specified.
2	/FI

     /FI:n     Specifies  that  only  file  n  on  the  tape  is to be
               considered.  n  is  decimal.  Note that /BL and /FI are
               mutually exclusive.
2	/EB

     /EB:n1:m1:n2:m2:... Specifies  fields  on  which  EBCDIC to ASCII
               conversion  is to be performed. Up to twenty fields may
               be defined and the parameters are:-
               n1 (etc.) - Starting  byte  position of field in record
                           (1-n)
               m1 (etc.) - Length of field to be converted.
               These values either apply from the start of each record
               (if /FX is specified) or from the start of each block.
               If    just  /EB  is  specified,  the  whole  record  is
               converted.
2	/PE

     /PE       Specifies  that  the  device MM: is phase-encoded (TU16
               1600  bpi).  This  switch does not apply to MT: devices
               and is default for MM:.
2	/AP

     /AP       Indicates  that  the  records  are to be appended to an
               existing output file.
2	/CO

     /CO       Defines the output file to be contiguous.
2	/CR

     /CR       Indicates  the  output  file is to have Carriage Return
               format (FD.CR set).
2	/FX

     /FX:n:m   This  switch may be specified either as an input switch
               or  an  output  switch and indicates that the blocks on
               tape contain fixed-length records.
               n     represents  the  length (in bytes) of the records
                     on tape.
               m      if specified, represents the length(in bytes) of
                      the  output  record.  This  must be less than or
                      equal  to  n, and if omitted defaults to n. This
                      is  used  so that fixed length input records can
                      be  truncated  before being output to disk (e.g.
                      80 byte card images truncated to 72 bytes).
               Note  that  the /FX switch affects 3 different areas of
               operation:-
               1) It  defines  each record to be written to the output
                  file.  In this case, and this case only, the records
                  are  allowed  to  span block boundaries, so that the
                  whole    range  of  blocks  under  consideration  is
                  considered as one large buffer.
               2) It  defines  each record to be translated by the /EB
                  switch.  In this case, records must fit exactly into
                  the blocks on tape.
               3) It  defines the record for the purpose of listing it
                  on  the  terminal  with the /FU switch. In this case
                  records must fit exactly into the blocks on tape.
               If  /FX  is  not  specified,  records are assumed to be
               variable length, and the same length as the tape blocks.
2	/TR

     /TR       Remove all trailing blocks from the output record. This
               switch  may  be specified with the /FX switch, in which
               case the output file is created as variable length with
               maximum  size  equal to the record-size. In particular,
               if  the  tape  contained  card  images  with a sequence
               number  in  columns  73  -  80, then /FX:80:72/TR would
               first  strip  off the sequence number and then truncate
               each record.
